possible cure for the 3B 'spark hop' issue?

[JP]

With a timing light? Which marks do you point the timing light at?

At the rotor through the hole you have just drilled in your spare dizzy cap which I described earlier on. Only reason you're using the timing light is so that the strobe effect makes it easier to see when the spark is central to the rotor tip.

[newsh]

Ok, you're looking through the hole into the dizzy. How do you know that 2000 rpm with the temp sender disconnected should be at the centre of the rotor tip though, are you saying theres an equal amount of advance and retard from that point? I'm really curious about this
What does the rotor tip represent in terms of timing angle from edge to edge? I guess its pretty easy if you have a rotor arm in front of you and a protractor, it will be double the angle from the centre to the 2 edges (cos it runs at half the speed of the crank).. so if thats say 15 degrees on the protractor then that will allow for 15 deg of advance and 15 deg of retard from the setting at 2000 rpm temp sens discon.?

[Jon441cc]

At the rotor through the hole you have just drilled in your spare dizzy cap which I described earlier on. Only reason you're using the timing light is so that the strobe effect makes it easier to see when the spark is central to the rotor tip.

This sounds interesting how many 3b's have you tried this on.


Jon.

[JP]

never tried this on a 3B engine this is just what we used to do on v8's when setting them up. Can't see it being any different though hence mentioning the method.

The 2000rpm with coolant sensor disconnected comes from the book values when setting static timing on the dizzy same value is used on G60 and G40 engines. Which if assuming your mark on the crank pulley is 100% would allow the spark to be dead centre on the rotor. By looking at the rotor itself you eliminate any discrepancy on the pulley markings.
Also the minute you start adding the coolant sensor to the equation it will advance/retard itself accordingly via the map on the ECU hence leaving it disconnected for the static setting.

Ultimately the basic principle of getting the spark to the centre of the rotor is that you have maximum range in +ve and -ve when it comes to the ECU controlling your timing without the risk of spark hop. Lining up hall windows and crank pulley marks etc will allow an engine to run and run very well 99% of the time. It's the 1% where you are trying to push the boat out and make the system in place work to it's limits where problems start occuring if not 100% correct.

It's like dialing in a set of cams where you are setting lift at TDC you can take them straight out the box and lob them into your engine and they will run fine. Dial them in to 0.01mm lift accuracy as per manufacturers spec and there is potentially some serious ponies to be gained. Ultimately it all comes down to how far you are trying to push things. I first learned the method when playing with my mates street driven camaro where 9.23 on the quarter wasn't fast enough so he started to chuck in serious amounts of nitrous. Currently he's down to 8.8's but it took a lot of setting up on the dizzy time wise to get that extra .5sec

[Simons]

I don't understand very much the first sentence, sorry...The resistor that you say, is the carbon brush??

The resistor is for suppressing radio interference, I don't think anything is going to happen to it if you upgrade the coil.

In spanish is condenser, capacitor...And it's for that you said, is it?

[Simons]

to see when the spark is central to the rotor tip.

Good trick!

+ a good coil

[dkw_dude]

Ok, you're looking through the hole into the dizzy. How do you know that 2000 rpm with the temp sender disconnected should be at the centre of the rotor tip though, are you saying theres an equal amount of advance and retard from that point? I'm really curious about this
What does the rotor tip represent in terms of timing angle from edge to edge? I guess its pretty easy if you have a rotor arm in front of you and a protractor, it will be double the angle from the centre to the 2 edges (cos it runs at half the speed of the crank).. so if thats say 15 degrees on the protractor then that will allow for 15 deg of advance and 15 deg of retard from the setting at 2000 rpm temp sens discon.?

Did a quick calculation on the rotor tip width/ignition advance "bandwith"
11mm tip width, ~157mm ID cap => ~25 degrees available edge to edge of tip. Multiply by 2 because of the crank/2 speed of the distributor, and then there should be ~50 degrees of advance to work on, - a few degrees for adjustment error and overlap.

I'm just trying to understand this stuff, please correct me if I'm way off the target here!

But on my S2 i have checked distributor adjustment with a scope (to get the timing pulse in the middle of the Hall window), and checked the 0 degrees point with a timing light (when I calibrated zero timing in VEMS) and at a point I had 42 degrees advance (4000 rpm/low load) when I listened for knock. At both occasions the engine ran smooth so I guess those points are "inside the limits".

This was on my specific s2, cannot guarantee for others.

[newsh]

Did a quick calculation on the rotor tip width/ignition advance "bandwith"
11mm tip width, ~157mm ID cap => ~25 degrees available edge to edge of tip. Multiply by 2 because of the crank/2 speed of the distributor, and then there should be ~50 degrees of advance to work on, - a few degrees for adjustment error and overlap.

I'm just trying to understand this stuff, please correct me if I'm way off the target here!

But on my S2 i have checked distributor adjustment with a scope (to get the timing pulse in the middle of the Hall window), and checked the 0 degrees point with a timing light (when I calibrated zero timing in VEMS) and at a point I had 42 degrees advance (4000 rpm/low load) when I listened for knock. At both occasions the engine ran smooth so I guess those points are "inside the limits".

This was on my specific s2, cannot guarantee for others.

Good info thanks.

[JP]

(to get the timing pulse in the middle of the Hall window)

Don't quote me on this but I have always been under the understanding that the trigger point is the leading edge of the gap i.e. the change. rather than the middle of the gap. At least that is what I was taught many a moons ago.

[dkw_dude]

Don't quote me on this but I have always been under the understanding that the trigger point is the leading edge of the gap i.e. the change. rather than the middle of the gap. At least that is what I was taught many a moons ago.

Ok not 100% sure about this myself, but seems to work ok the way it is now! Running VEMS as the signature says, not sure if it works exactly as the Motronic regarding trigging.

[mouse]

Don't quote me on this but I have always been under the understanding that the trigger point is the leading edge of the gap i.e. the change. rather than the middle of the gap. At least that is what I was taught many a moons ago.

This - sort of - was the way it works with distributor engines without an ecu. Advance is implemented by centrifugal advance (a couple of spring loaded weights below the distributor which changed the position of the rotor (and breaker point cam on its shaft) depending on rotation speed) and vacuum advance (which I cant remember the exact mechanism now).
Although the trigger is not the leading edge of the rotor arm but the opening of the breaker point in the distributor.

Out of curiosity - does an engine with and ecu and a distributor like the 3B have any mechanical advance for the rotor or does it not need it because all timing can fall within the rotor tip width as desribed above?

[dkw_dude]

No mechanical on advance on the 3B!

[Simons]

Out of curiosity - does an engine with and ecu and a distributor like the 3B have any mechanical advance for the rotor

Fiat 1 Turbo phaseI?? Tomorrow I will look at becouse I have a complete engine and wiring to swap into fiat X1/9....when I have spare time or another life...

No mechanical on advance on the 3B!

Correct, and if the sensor hall is damaged or broken the ecu could calculate the timing signal thanks at the r.p.m signal and the ecu retard 6º the timing, this only happend if the engine are run, if you stop the engine, it can not starts again.

The ecu adjust the timing due to the throley possition, knock sensors, temp. sensors, some sensor bad(like hall, maf, knock sensor-if it's bad the 1st, retard 6º the timing on cylinders 1.2.3 and if it's 2nd, retard 6º on cylindres 4.5)

[Simons]

This bosch nr. is for the 11mm rotor arm 1 234 332 350 R1

This bosch nr. is for the 18mm rotor arm, the correct bosch nr. for the 11mm arm is 123433 2414 R1

The bosch dizzy cap is 1235 522 404

The bosch(I think, his name is on it) protector dizzy cap is 0 290 004 035

Fiat 1 Turbo phaseI

No, I take a look and the coil is controled by the ecu and the dizzy can not allow any adjustment

[denniselbows]

Has anyone had or heard of a spark hop/pre ignition failure when the correct rotor arm was used